Create animation videos from 3D joint positions
You start with a blend file that contains a mesh which defines the appearance of your character. You then have an armature, which is made up of a collection of bones that deforms your character mesh. The armature is then used by an animator to control the position of the character during an animation.

The script you have takes a pre-recorded list of locations and automates the animation of the armature instead of someone manually animating it.

The line rig = objs['myrig'] is referring to the armature named 'myrig' that you have setup to deform your character, this needs to be an armature with bones matching the names in your mocap data, not an empty.